1. Field of the Invention
The present invention relates to a conductive circuit portion of a flexure used in a disk drive for an information processing apparatus such as a personal computer, in particular, relates to an interleave circuit.
2. Description of the Related Art
A hard disk drive (HDD) is used in an information processing apparatus such as a personal computer. The hard disk drive comprises a magnetic disk rotatable about a spindle, carriage turnable about a pivot, etc. A disk drive suspension is disposed on an arm of the carriage.
The disk drive suspension comprises a baseplate, a load beam, etc. A flexure is located on the load beam. A slider is mounted on a gimbal portion formed near a distal end of the flexure. The slider is provided with elements (transducers) for accessing data, that is, for reading or writing data. The suspension, the flexure, etc., constitute a head gimbal assembly.
Various types of flexures have been put to practical use according to the required specification. A flexure with conductors, for example, is known. A conductive circuit portion of the flexure with conductors includes a metal base made of a thin stainless steel plate, an insulating layer made of an electrically insulating material, such as polyimide, which is formed on the metal base, a plurality of copper conductor members which are formed on the insulating layer, etc. Ends of the conductor members are connected to elements (for example, an MR element: a magneto resistive transducer) of the slider. The other ends of the conductor members are connected to an amplifier or the like of the disk drive.
The impedance of a conductive circuit portion of the flexure is expected to be reduced in order to match the amplifier and the elements of the slider and also to reduce energy consumption. The inductance is also expected to be reduced. Further, to enable higher-speed data transfer, properties that attenuation is low even in a high-frequency band (i.e., low-attenuation properties) are required. In order to meet such a requirement, a flexure with conductors comprising multi-trace transmission lines is effective. A conductive circuit portion comprising the multi-trace transmission lines is also called an interleave circuit. A flexure comprising the interleave circuit is suitable for high-speed data transfer since attenuation in a high-frequency band is low.
JP 4547035 B (Patent Document 1) or JP 2013-182649 A (Patent Document 2) discloses an example of an interleave circuit. Each of conductor members of the interleave circuit diverges into two lines. However, according to the study of the inventors of the present invention, it has been found that increasing the number of divergence of each of the conductor members (the number of branch conductors) enables the achieving of lower impedance and lower attenuation.
However, in a conventional interleave circuit, the more the number of branch conductors is increased, the more the connecting terminals of those branch conductors are increased. These connecting terminals are connected to an electrode pad via conductive members such as bonding members, respectively. Accordingly, an increase in the number of connecting terminals means that the number of conductive members is increased, and the interconnect structure of the connecting terminals with respect to the electrode pad also becomes complicated. Consequently, a problem arises that it becomes difficult to arrange a conductor branch portion within a limited narrow area of the conductive circuit portion.